Syllable 0.6.4 has been released. "Syllable 0.6.4 contains many new features, enhancements and bug fixes from previous releases. Highlights of this release include a new version of ABrowse; the web browser has been re-written using the WebKit engine. A new version of Whisper, and the Contact address book is now included. A large number of usability and user interface fixes, largely curtesy of Anthony Morphett. New drivers for the SysKonnect Yukon1 network cards & ACPI CPU management and updated drivers for Radeon, GeForceFX, SiS and Trident video cards, HD Audio, Intel & VIA SATA controllers and Realtek 8169 network cards. The usual clutch of bug fixes and enhancements."

It's a great browser, but it does have limitations. Specifically, the XUL user interface isn't native on any platform. Now, it's really good on several platforms (Windows, OS X, and Linux), but that still doesn't make it native.

If you're an alternative OS it might make a lot more sense to choose an easily embeddable rendering engine inside a native GUI. WebKit offers them that opportunity. If they wanted to port Firefox, they'd have to get XUL running on their platform which is no small task - and running with near-native performance and consistency to be considered good.

These people know the API kits they've helped create and choosing WebKit doesn't loose them much, if anything. WebKit is arguably better at scripting, ajax, and HTML rendering than Firefox. And, as people have pointed out, flash has nothing to do with it being Firefox or not. Safari on Windows and Mac does flash fine.